Water-cooling tower



June 20, 1950 N. P. GREEN WATER-COOLING TOWER 2. Sheots-Shqet 1 FiledDec. 26, 1947 June 20, 1950 I N. P. GREEN 2,512,271

I WATER-COOLING TOWER Filed Dec 26, 1947 2 Sheets-Sheet 2 7 FIGS.

Patented June 20, 1950 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to water-cooling towers, and more specifically toheat-exchange apparatus for receiving water from industrial equipmentand atmospherically cooling the water for subsequent return to theequipment.

Among the several objects of the invention may be noted the provision ofa water-cooling tower in which increased heat-exchangecapacity isobtained; the provision of apparatusof the class describedin whichsaidincre'ased heat-exchange capacity is obtained with a reduction inboth water-pump and air-fan power; the provision of apparatus of thisclass which requires only a single water-pumping operation for "anyeiiiciency; and. the provision of apparatus of this class which issimple in operation and flexible and economical to build. Other objectswill be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements. and combinations ofelements, features of constructionand arrangements of parts which willbe exemplified in the structures hereinafter described, and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawings, in which one of various possibleembodiments of theinvention is illustrated,

Fig. 11 is a cross section taken through a typical form of apparatus:embodying .theinvention, parts being broken away and, shown in section;

.Fig. 2 is a diagrammatic top plan view on a reduced scale, showing atypical assembly of units;

Fig. 3 is a horizontal. section taken: on line 3-3- of Fig. 1;

Fig. 4 is a horizontal section taken on line 4-4 of Fig. 1; and,

Fig. 5 is a vertical section taken on line 55 of Fig. 4.

Similar reference characters indicate corresponding parts throughout theseveral'views' of the drawings.

I have discovered that the efliciency and the heat-exchange capacity ofa cooling tower can be increased for a givenexpenditure of energy'inauxiliaries such as water pumps, fansand the like by:

(1) Subjectinga gravity'fiow of water to serial passage through coolingcompartments of cross sections which are comparatively small relative tothe air-carrying crosssection of the tower;

(2) Causing thecurrent of cooling air to be completely divided so assimultaneously to have parts of it come into separate heat-exchangerelations with the serially flowing; waterin theItspe'ctivecompartments; and, V

(3) Enforcing an exclusive and complete coun terflow between'eachdivided mass of air andthe water in a given compartment.

The cross section of a tower is primarily determined by the air flowwhich must be accommodated. Heretofore the procedure has been generallyto break up a desired mass of water throughout the cross section of atower and to treat this broken mass with the entire flow of air eitherby cross flow, counterflow, or both. This has resulted in an excessiveamount of interspacebetween the drops of water through which air passedwithout coming into sufliciently close proximity to the water formaximum heat exchange.

Counterflow action between the air and the Water is the best forobtaining maximum heat transfer during a given contact between air andwater. By means of the present invention, I-'arrange a tower so that itscross section accommodates the entire air flow but the cross sectionover which the broken water is distributed is less than that of theentire tower, and in this smaller cross section I' obtain truecounterfiow between all of the water and a definite part of air. This,with resulting increase in heat exchange, is ac complished with a simpleconstruction requiring a minimum of pumping energy and mechanicaloperations.

Referring now more particularly to the drawings, numerals I (Fig. 1)indicate individual towers or stacks which maybe placed in variousarrangements, one of which is shown in Fig. 2. In this arrangement thetowers I are abutted back to back to form pairs which are then abutted'side to side to form a line, as indicated. Other multiple arrangementsmay be made and it is to be understood that'the essentials of theinvention can be carried out in any one tower and that the particularmultiple arrangement shown is only exemplary. However. in the case ofthe said abutted arrangement shown, the necessity for dividing wallsbetween abutting towers is eliminated. For example, in Fig. I no wallsare needed where the towers abut. but such could be employed if desired.

Each tower l comprises a bottom sump 3 above which is a suitablesuperstructure having an upper outlet 5 in which is a fan driven from amotor 9 through a transmission ll. Below each fan is a drift eliminatorsection 2, which is in the nature of bathing to reduce the escape ofairentrained moisture.

At" an elevated position is located a water-sup ply container [3. Onecontainer may supply several towers. This. container [3 includesoutlets;

l5 communicating withlateral channels II. Adjustable control plates areshown at 19, these being operable from control apparatus 21. Water issupplied to the box from the hot water supply through a riser pipe 23.

The channels I! lead outward from the container 13 to points abovegroups of cross channels 25, located near the top and sides of thetowers (Fig. 3). Holes [8 in channels I! allow water to gravitate to thecross channels 25 from which the water subsequently flows over serratededges 20. Under the channels 25 are built angle-shaped heat-exchangeboxes 21. Each box includes an enclosing vertical inner imperforate wall29 and an enclosing horizontal bottom-rimmed imperforate wall forming acollecting basin 3L In the bottom of the basin 3| is a trough 33 whichextends inward and over another set of channels 25 associated with asecond and lower box 31. Openings [8 in trough 33 allow water'to escapedown into the cross channels 25 from which it escapes over serratededges 20. This box 31 also has an inner wall 29 and a collecting basin3| with a trough 33 leading out to holes i8 over a third group ofchannels 25 having serrated overflow edges 20 and which are above whatwould be a third box if a back wall were used for this tower. This willbe considered to be a third box 41 for reasons which will appear. Itwill be understood that the above described descending steppedconstruction may be carried out in as many steps as may be desired, thethree-stepped arrangement being merely typical.

Under each set of cross channels 25 is a socalled filling section 39. Asknown in this art, a

filling section is one constituted by bafiles over which the water flowsand drips and through which flow of cooling air is admitted. Suchbaifies may be constructed of wood, metal or the like, and are oftencomposed of a cries-cross arrangement of strips of rectangular crosssection, preferably with the planes of the sections vertically arrangedso as to present a large area of wetted surface With minimum obstructionto air flow. Any water flowing through such filling or baflling isbroken up and in addition to running over the baflles, drips or rainsdown between them. The filling sections are diagrammed b crosses overthe areas occupied thereby and will not further be detailed in view ofcommon knowledge regarding their make-up. The filling sections extendonly partially downward in the respective boxes 21, 31 and 41, leavingopen areas 35 into which air may be introduced through openings 4|,provided at the lower left of each space 35. In the case of thelowermost equivalent box 41, the opening M of course extends down to thelevel W of the liquid carried in the sump 3. The depth of each stack lperpendicular to the plane of the paper in Fig. 1 is optional and assuggested in Figs. 3, 4 and 5, for increased depths the unitconstruction shown may be repeated.

The front of each tower is covered by louver boards 43 which admit astream of air constituting all of the air flow employed in each tower.This stream is separated into three paths A, B and C, which respectivelysupply the boxes 21, 3'! and 51. lower streams C ofiset one anothercentrally and act as mutual guides in a vertical plane such that nocentral box wall corresponding to walls 29 of boxes 2'! and 31 is neededfor the equivalent box 41. Such a wall could be employed if desired forbox 41. In the case of abutted towers one back wall for box 41 wouldserve both bottom boxes 41.

Since the towers are abutted, the

It should :be understood that the use of the fans I is optional and thatunder certain circumstances natural convection may be relied upon forenforcing air flow through the tower. The fans, however, substantiallyincrease capacity.

Operation is as follows, assuming that the fans I are operating and thata suitable standard pump (not shown) in the line 23 pumps hot water tothe container I3. Water flows from the container I 3 through the troughs11, through openings l8 to the upper channels 25, where it isdistributed laterally and overflows into the filling 39 of each upperbox 21. The filling baffles break the water up so that it drips or rainsdownward from the filling. Considering for the moment one tower only,water is collected in the basin 3| and enters the trough 33 below box21. It then flows through openings I8 into the channels 25 of the nextbox 31 and overfiowsinto its filling 39 and rains down onto the basin 3|of this box 31 from whence it enters its troughs 33, to be deliveredthrough another set of openings Hi to channels 25 of the lowermost box41. It overflows these channels into the filling 39 of this lowermostbox and then rains down into the supply at the sump 3.

All of the atmospheric air used is drawn in through the louvers 43 andpasses out of the outlet 5. This air is divided into the three distinctstreams A, B and C, as determined by the forms of the boxes 21, 3! and41. These streams enter the spaces 35 and are deflected upward intocomplete and isolated counterflow movement relative to the downwardlyprogressing water. Air stream A contacts the hottest water; air stream Bcontacts cooler water; and air stream C contacts the coolest water. Itis clear from the above that the number of steps in the heat-transferoperation could be increased by increasing the number of boxes andconsequent air streams. Since the temperature drop between the water andthe air stream A is th highest, the most efficient heat transfer isobtained in box 21. This efiiciency decreases in successive boxes indescending order, but the average efiiciency of all boxes in a series ishigher than if all the water were placed in heat-exchange relation withall of the air operating in a single stream. That is to say, theenthalpy (or total heat) of the air is by this means more eflicientlyincreased than heretofore. It will be noted that all of the water whichflows through the successive boxes '21, 31 and 41 is caused to rainthrough a cross section which is roughly times the total cross sectionof the tower where N is the number of boxes employed. In this case thefraction will be approximately one-third. Thus the air which travelsthrough this reduced cross section is thrown into more intimate relationto the water droplets without so much air getting through a givenprocess in a box at low heat-exchange efficiency. This eificiency isenhanced by the enforcement of true counterfiow conditions between thewater and the air in each separate heattransfer process in each box. Itis true that the temperature difierence between the water and air goesdown with each passage of the water through a successive box and thitends to reduce theamp-ii enthalpy increase of the air passing througheach successive box, but the losses in this respect are more than madeup for by the advantages stated, so that the total enthalpy increase ofthe total air flowing from each outlet 5 is higher than heretofore. Theconstruction above described can b carried out in various forms, but theessential features are that:

(a) The hot water flows serially and by gravity through the respectivefiller sections of the boxes 21, 31 and 41, the successive coolingfunctions 'being serial in time, the cross sections of the respectivefiller sections being smaller than that of a given stack by the ratio of(b) The air masses in the streams A, B, C function simultaneously butseparately upon the stream of water flowing serially through the boxes21, 31 and 41; and,

(0) Each isolated mass or stream of air in its respective compartmentconstituted by boxes 21, 31 and 41, flows upward against the descendingbroken stream of water in true counterfiow relationship.

In the above expressions, where the factor N is used, it will beunderstood that it is assumed that all boxes are of the same sizes andif they are not, then the expression for each box needs to be modifiedin a manner which is obvious.

It should be noted that the boxes 21, 31 and 41 form distinctly enclosedcompartments carrying filling means to which liquid is introduced fromabove the compartment and below which the air is guided for upwardcounterfiow in respect to the descending water, and that the respectivestream of air flowing through the compartment is definitely separatedfrom other air streams and guided by the walls of the compartment, thelower wall of the compartment forming a catch basin from which waterprogresses to the next compartment without letting air through thecompartment from any other air stream. It will also be noted that eachfilling means is completely surrounded by a wall which Will enforcevertical counterfiow in the respective compartment so that theheat-exchange functions in the respective compartment take place in anisolated region. Since the flow cross section of each compartment isless than the flow cross section of the entire tower or stack, saidisolated heat-exchange process in the respective compartment takes placeunder optimum mechanical conditions for optimum heat-exchange functions.7 By means of the structure described, the entire cross section of thestack is available to all of the air flowing into the louvers 43, butonly a fraction of the cross section of the stack is available tocounterfiow between water and air in any given compartment.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As many changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

I claim:

1. A cooling tower comprising a vertical stack having a common verticalside air inlet and a common horizontal upper air outlet, a series ofheat-exchange boxes each consisting of imperforate L-shaped baffleelements arranged in diagonal stepped relation from an upper part of thestack adjacent the air inlet and air outlet to a lower part of the stackdistant from the air inlet and air outlet, peripherally enclosed fillingbaiiles respectively horizontally arranged crosswise in the upperportion of each box, the bottom of each box forming a water-collectingbasin spaced from the respective filling bafile so as to provide anindividual box inlet directed toward said vertical air inlet, eachsuccessive downward box inlet being farther from the common air inlet,means for introducing all the water to be cooled into the fillingbailles of the uppermost box for progress to its basin, means fortransferring all of the water from said basin to the filling bafiies ofsuccessively lower boxes, whereby all the water passes serially throughthe filling baflles and basins of all stepped boxes and the air enteringsaid vertical inlet is divided between said respective box inlets, eachdivided portion of air being deflected by a respective L-shaped baffleelement into respective upward counterfiow relationship with all of thewater which passes through the respective box.

2. A cooling tower comprising a vertical stack having air inlet meansand a common horizontal upper air outlet, a group of heat-exchange boxesarranged in diagonal stepped non-overlapping relation from an upper partof the stack adjacent the air outlet to a lower part of the stack moredistant from said air outlet, peripherally enclosed filling bafflesrespectively arranged crosswise in the upper portion of each box, thebottom of any box which is higher than another forming a water-coolingbasin below its respective filling, means for introducing substantiallyall the water to be cooled into the filling baffles of the uppermostbox, means for transferring all of the water from any higher basin tothe filling baifies of a successively lower box, whereby all the waterpasses serially through the stepped boxes, and baflle means constitutedby parts of the boxes adapted to divide the air flow from the air inletmeans into exclusive individual counterfiow relationships with all theWater passing serially through the respective boxes.

NATHANIEL P. GREEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,054,809 Fleisher Sept. 22, 1936FOREIGN PATENTS Number Country Date 10,448 Great Britain Oct. 22, 1907550,268 France Dec, 8, 1922 718,790 France Nov. 5, 1931

